1. Field of the Invention
The invention relates generally to handling, routing and shipping containers. More specifically, the invention relates to systems and methods for automatically placing lids on, and removing lids from, shipping containers.
2. Description of the Related Art
It has been a common practice in the shipping and package delivery industry to ship items in trays such as flat trays and SPBS trays (tubs). Items such as letters and packages are placed in trays, a lid is put on them, and a strap is bound around the tray and lid assembly. One reason for this practice is to protect items from damage and loss during shipping. Also, storing and stacking uniform assemblies is more efficient in terms of time and space, than storing disparate items.
However, putting lids on trays and strapping the assembly at an intermediate location, only to have the strap cut and lids taken off so items can be further routed, is a time consuming and repetitive task. Typically, this task is done manually. A worker receives the assembly, manually cuts the strap, removes the lid, unfolds the lid, sorts and stacks the lid according to size, and feeds the un-lidded tray to the next station. Then, after the items have undergone the required processing at the intermediate location, a worker reverses this time consuming process. The worker selects the appropriate size lid for the tray, folds it, places it on the tray, puts a strap on the assembly, and feeds it to the next station. This manual process is both time-consuming and expensive. Further, the manual process subjects workers to the hazards associated with physically handling a cutter and a large numbers of trays. An automated process to place lids on trays and to remove lids from trays would provide an advantage over a manual system.
One problem associated with putting lids on trays has been that items tended to get damaged when the lids are placed on the tray. The unfolded lids usually have four flaps, each corresponding to a tray side, in the finished assembly. Two opposing outside flaps remain outside of the tray and the other two opposing inside flaps reside inside the tray between the items and tray sides. Problems arise, however, because the inside flaps can jam against items, such as letters, that are close to the edges of the tray. In the past, careful attention was needed to ensure that items were not damaged when lids were put on trays.
One problem associated with putting lids on trays has been that items tended to get damaged when the lids are placed on the tray. The unfolded lids usually have four flaps, each corresponding to a tray side, in the finished assembly, two opposing outside flaps remain outside of the tray and the other two opposing inside flaps reside inside the tray between the items and tray sides. However, problems arise because the inside flaps can jam against items, such as letters, that are close to the edges of the tray. In the past, careful attention was needed to ensure that items were not damaged when lids were put on trays.
Accordingly, there is a need for an automated system and method for putting lids on trays and for removing lids from trays. A need also exists for a system that can perform these functions without damaging items in the trays, and to be fed into a device that will put a strap around the assembly. It would be desirable to provide a method that obtains the advantages of the present system while minimizing the need for expensive automated equipment.